Field of the Invention
The present invention relates to an image capturing apparatus, a control method of an image capturing apparatus, and an image processing method.
Description of the Related Art
Conventional image capturing apparatuses transform raw image information (RAW image) captured by an image sensor into signals including luminance signals and color difference signals, and apply, to each signal, so-called development processing, which includes denoising, optical distortion correction, image optimization, etc. Usually, the luminance signals and color difference signals that have undergone the development processing are compression-coded and recorded on a recording medium.
Some image capturing apparatuses, however, are capable of recording RAW images. Although RAW images have a vast amount of data to be recorded, they have the advantage of not being altered or degraded from the original image, and being editable after shooting.
A configuration of an image capturing apparatus that records RAW images is disclosed in Japanese Patent Laid-Open No. 2011-244423. Japanese Patent Laid-Open No. 2011-244423 discloses a configuration for recording development parameters together with a RAW image, and then developing and playing back the RAW image by using the development parameters.
Also, Japanese Patent Laid-Open No. 2004-222148 discloses a configuration that is applicable to the case of a sensor that has pixels each including two photoelectric conversion areas (a high-sensitivity area and a low-sensitivity area), and according to this configuration, image data sets obtained from the high-sensitivity pixel and the low-sensitivity pixel are separately recorded as RAW data sets onto a recording medium. This configuration provides a recording method that realizes images that can be processed easily even in the case where image synthesis is performed outside the camera.
In addition, a sensor that has pixels each including two photoelectric conversion areas is also capable of obtaining data of two images that have a parallax, when the two areas are configured to have a same sensitivity. It is also possible to calculate the image defocus amount by detecting the relative positions of the subject captured in the two images, and to perform image processing such as focus readjustment (refocusing) according to the defocus amount.
Image capturing apparatuses in recent years have an advanced image sensor, and the number of pixels in one image is increasing. The number of successive images that can be taken per second is also increasing. For these reasons, the amount of processing involved in RAW image development processing, such as debayering, denoising, and optical distortion correction, is accordingly increasing, and, in some cases, development processing performed in parallel with shooting requires an extremely large proportion of the ability of the circuitry or a large amount of power consumption. It can also happen that the performance of shooting is degraded by development processing occupying the circuitry or imposing a limitation in terms of power consumption, for example.
On the other hand, a configuration for recording RAW images without developing them, as with the configuration disclosed in Japanese Patent Laid-Open No. 2011-244423 described above, can reduce the amount of processing for development during shooting. However, since images are recorded in an undeveloped state, it is difficult to promptly play back and display the images, for example. Furthermore, it is possible that RAW images cannot be played back (or developed) by other devices. Therefore, conventional methods of recording RAW images sometimes cause inconvenience to users.
In addition, in the case of a configuration for recording RAW images without developing them as with the configuration disclosed in Japanese Patent Laid-Open No. 2011-244423 described above, dynamic range adjustment or the likes are sometimes performed during developing and editing after shooting, by using the image information acquired from high-sensitivity pixels and low-sensitivity pixels as disclosed in Japanese Patent Laid-Open No. 2004-222148 described above. However, there are cases where users wish to perform a focus adjustment based on image phase information acquired from the pixels. In such cases, information of each of the pixels is desired to be recorded on a recording medium. For this purpose, Japanese Patent Laid-Open No. 2004-222148 described above proposes a method of recording image data sets as separate RAW data sets onto a recording medium. However, this method increases the amount of recording data and reduces the available storage capacity, and sometimes causes inconvenience to users.
As described above, in order to realize high shooting performance, high recording performance, and high-speed playback of images by using a conventional apparatus, the apparatus is required to be equipped with high-performance circuitry and to perform high-output driving in some cases. Such a conventional apparatus is also required to be equipped with a large-capacity recording medium for recording RAW images, and to perform high-speed playback in a simple manner in some cases.